ACUTE ABDOMEN IN INTENSIVE CARE UNIT: ETIOLOGY, COMORBIDITY AND SEVERITY OF 1,523 PATIENTS

ABSTRACT BACKGROUND: Clinical features and outcomes of patients admitted to the intensive care unit due to acute abdomen are important to be investigated. AIMS: To evaluate the outcomes of critically ill subjects with acute abdomen according to etiology, comorbidity and severity. METHODS: Outcomes of 1,523 patients (878 women, mean age 66±18 years) consecutively admitted to a specialized gastrointestinal intensive care unit with different causes of acute abdomen from January 2012 to December 2019, were retrospectively evaluated according to etiology, comorbidity and severity. RESULTS: The most common causes of acute abdomen were obstructive and inflammatory, particularly large bowel obstruction (27%), small bowel obstruction (18%) and acute pancreatitis (17%). Overall mortality was 13%. Surgery was required in 34% of patients. Median length of stay in the hospital was 9 [1-101] days. On univariate analysis mortality was significantly associated with age, APACHE II, Charlson comorbidity index, requirement for surgery and malignancy (p<0.0001), but only APACHE II, Charlson comorbidity index and surgical interventional remained significant on multivariate analysis. CONCLUSIONS: Critically ill patients admitted to the intensive care unit with acute abdomen constitute a heterogeneous group of subjects with different prognosis. Mortality is more related to the severity of the disease, comorbidity and need for surgery than to the etiology of the acute abdomen.


A QUEDA DA PRESSÃO PORTAL APÓS DESVASCULARIZAÇÃO ESOFAGOGÁSTRICA E ESPLENECTOMIA INFLUENCIA A VARIAÇÃO DO CALIBRE DAS VARIZES E AS TAXAS DE RESSANGRAMENTO NA ESQUISTOSSOMOSE NO SEGUIMENTO EM LONGO PRAZO?
Does the drop in portal pressure after esophagogastric devascularization and splenectomy variation of variceal calibers and the rebleeding rates in schistosomiasis in late follow-up?
Walter de Biase SILVA-NETO 1 , Claudemiro QUIRESE 1 , Eduardo Guimarães Horneaux de MOURA 2 , Fabricio Ferreira COELHO 3 , Paulo HERMAN 3 ABSTRACT -Background: The treatment of choice for patients with schistosomiasis with previous episode of varices is bleeding esophagogastric devascularization and splenectomy (EGDS) in association with postoperative endoscopic therapy.However, studies have shown varices recurrence especially after long-term follow-up.Aim: To assess the impact on behavior of esophageal varices and bleeding recurrence after post-operative endoscopic treatment of patients submitted to EGDS.Methods: Thirty-six patients submitted to EGDS portal pressure drop, more or less than 30%, and compared with the behavior of esophageal varices and the rate of bleeding recurrence.Results late post-operative varices caliber when compared the pre-operative data was observed despite an increase in diameter during follow-up that was controlled by endoscopic therapy.Figure 1 -Causes of acute abdomen leading to admission to the intensive care unit.

Conclusion
All patients were followed according to the hospital protocol 2 , which has been constantly updated according to international guidelines.
Patients in palliative care were excluded from the analysis.Patients were followed until death or hospital discharge.The primary endpoint was in-hospital mortality.
The study was approved by the Research Ethics Committee of Hospital Português (number 26195719.0.0000.5029).

Statistical analysis
The variables are presented in text and tables as numbers and percentage.Clinical and laboratory features were compared using the chi-square or Fisher's test.Continuous variables were reported as mean and standard deviation (SD) or as median and interquartile range, respectively, whether the distribution was normal or skewed, using the Student t test or the Mann-Whitney U test.Variables associated with mortality at univariate analysis with a p-value of <0.10 were entered in multivariate logistic regression modeling using stepwise elimination.The software used for analysis was the Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, EUA), version 14.0 for Windows.

RESULTS
One thousand five hundred and twenty-three patients (878 women, mean age 66±18 years) were admitted to the ICU with an AA between January 2012 and December 2019.The clinical and laboratory data and outcomes of those subjects are in Table 1.
Approximately 2/3 of those patients are discharged from the ED, particularly those with nephrolithiasis, NSAP and non-complicated inflammatory acute abdomen, but patients with life-threatening disorders with actual or impending organ failure or significant comorbidity due to a higher risk of complications and death are usually admitted to intermediate or intensive care units (ICU) for real time monitoring of organ function, management of associated sepsis or hemodynamic optimization before or after urgent or even elective surgery 12,19 .
One recent Brazilian study has evaluated the incidence and mortality of patients with AA admitted to the hospital through the Brazilian Unified Public Health System (SUS) 18,22 .The most common causes were CC, acute appendicitis, AP, complications of gastric and duodenal ulcers, acute diverticulitis and inflammatory bowel disease (B),(C).The authors have noted an increase in the frequency of acute appendicitis, AP and acute diverticulitis over the years.Mortality due to complications of gastroduodenal ulcers, acute diverticulitis and AP was higher when compared to other causes of AA 18 .
There are few studies concerning the most frequent causes of AA in patients admitted to the ICU and their outcomes in respect to requirement of surgical intervention, length of stay (LOS) and mortality 3,13,27 .There is also limited data evaluating the impact of baseline clinical and laboratory scores, such as acute physiology and chronic health evaluation (APACHE) II and Charlson Comorbidity Index (CCI) in assessing prognosis 13 .
The purpose of this study was to evaluate the epidemiology and outcomes of patients with AA admitted to the ICU in a tertiary care hospital in Brazil as well as to investigate risk factors associated with mortality.

METHODS
All patients admitted to the Gastroenterology and Hepatology Unit of the Hospital Português in Salvador (BA), with the diagnosis of AA from January 2012 to December 2019, were retrospectively analysed.This facility is an intensive gastrointestinal ICU specialized in management of critically ill patients with gastrointestinal disorders, such as AA, gastrointestinal hemorrhage, decompensated cirrhosis and acute liver failure, as well as patients in the postoperative period of major abdominal surgery.
Comparison of demographics, clinical data and outcomes according to the cause of AA is in Table 2. Patients with OAA, VAA and PAA were significantly older when compared to those with other causes of AA.On the contrary, patients with IAA and TAA had lower APACHE II levels at admission when compared to their counterparts with OAA, PAA, HAA and NSAP.In addition, comorbidity, when assessed by CII, or the presence of cancer was higher in patients with OAA, PAA and HAA.In respect to outcomes, surgical intervention, as expected, was required more often in patients with PAA and TAA.Inflammatory AA and TAA had lower mortality rates, whereas LOS was higher in patients with OAA, TAA and PAA (Table 2).
In respect to the most common causes of IAA, acute diverticulitis and CC were seen more frequently in older patients (Table 3).Cholecystitis and/or cholelithiasis were more commonly observed, with higher APACHE II scores and CCI and required more often surgical intervention.Other causes of IAA had more often concurrent cancer.These patients had the longest LOS and higher mortality when compared to other with AP, acute diverticulitis or even CC (Table 3).
Patients with OAA were categorized as malignant and non-malignant LBO and SBO and other causes due to gastric AA: acute abdomen; LBO: large bowel obstruction; SBO: small bowel obstruction; OAA: obstructive AA; HAA: hemorrhagic AA; NSAP: non-specific abdominal pain; TAA: traumatic acute abdomen; PAA: perforated AA; VAA: vascular AA.Patients with malignant obstruction had higher APACHE II scores and CCI and longer LOS when compared to those without cancer.When compared to other patients, surgery was more commonly indicated in those with malignant LBO and mortality was significantly lower in non-malignant SBO (Table 4).
Mortality after emergency surgery was shown to vary between 9 to 19.4% 6,9,25,[28][29][30] .Pucher et al. 25 have evaluated outcomes of 748 patients with AA requiring emergency major abdominal surgery.Most of them had adhesions, ischemia or bowel perforation and almost half required ICU admission.Only 9% died in hospital and mortality was associated with severity and comorbidity, respectively assessed by ASA grade and P-POSSUM morbidity.In contrast, Clarke et al. 9 found higher 30-day mortality rates after emergency surgery, particularly in those subjects older than 80 years, and when compared to our study.Ukkonen et al. 30 reported similar postoperative 30-day mortality rates, which were also correlated with increasing age, severity and comorbidity including malignancy.
Few studies have investigated the outcome of patients admitted to the ICU with AA 13,28 .Most of them enrolled patients who developed AA after ICU admission, mostly due to VAA or IAA with a high mortality rate related to late diagnosis and surgical intervention 13,28 .To our knowledge, our study is the first investigation concerning the fate of patients with AA admitted to a dedicated gastrointestinal ICU for either conservative management or in the perioperative period either before or after emergency surgery.This is a single-centre study with some limitations due to its retrospective design and lack of follow-up after hospital discharge.It is also important to acknowledge that it was performed in a tertiary care center, with a risk of selection bias and overestimation of severity and mortality of those patients who were included in the analysis.Several other studies have dealt with outcomes of subjects hospitalized due to AA with or without requirement of intensive care support 21,23 .Symons et al. 29 reported outcomes of more than 350 thousand patients who were hospitalized with the diagnosis of life-threatening surgical conditions in different hospitals from the National Health System (NHS) of the United Kingdom from 2000 to 2009.More than half of those patients had OAA and the remaining had miscellaneous causes of IAA, PAA or VAA.Overall, 30-day mortality was 15.8%, varying from 7.44 to 47.5% according to the underlying diagnosis.In accordance with our findings, mortality was higher in those with bowel ischemia, older age and higher Charlson scores.Surgical intervention was also required in roughly 1/3 of the patients.Of note, low mortality rates were observed in institutions with higher availability of ICU and high-dependency beds and better imaging resources.
Recently, another analysis of the NHS database described an even lower mortality rate, but most of the patients had AP or acute appendicitis with a lower inherent risk of death 23 .In this report, lower mortality was also observed in hospitals with higher levels of medical and nursing staffs, greater number of operating theatres and critical care beds.
In Brazil, one report from the IT Department of the SUS (DATASUS) evaluating outcomes of patients hospitalized with the codified diagnosis of AA described a crude mortality rate of only 9.62% 21 .Lower rates were even described in another temporal analysis from DATASUS involving only patients with non-traumatic AA 18 .Those discrepant results could be attributed to differences in disease severity and profile and frequency of concurrent comorbidity that were much more frequent in our cohort of critically ill patients.

CONCLUSION
Finally, the patients admitted to the ICU with AA due to disease severity, organ dysfunction or comorbidity constitute a heterogeneous group of subjects with different prognosis according to the type of AA, age, disease severity, comorbidity and concurrent malignancy.Those latter variables, however, are more correlated to adverse outcomes than the categorized cause of AA leading to hospitalization.

Figure 1 -
Figure 1 -Causes of acute abdomen leading to admission to the intensive care unit.

Table 1 -
Clinical and laboratory features and outcomes of patients admitted to the intensive care unit with acute abdomen (n=1,523) APACHE II: acute physiology and chronic health evaluation II.ORIGINAL ARTICLE2/6ABCD Arq Bras Cir Dig 2023;36:e1778

Table 2 -
Clinical features and outcomes of patients admitted to the intensive care unit according to the acute abdomen classification.obstruction.Comparison of demographics, clinical variables and outcomes in patients with OAA revealed significant differences, in respect to age, APACHE II score, CCI, frequency of cancer, requirement of surgery, LOS and mortality.In this respect, patients with LBO were older when compared to other with SBO.

Table 5 -
Univariate and multivariate analysis of variables associated with mortality in subjects admitted to the intensive care unit with acute abdomen.
CCI: Charlson Comorbidity Index; APACHE II: acute physiology and chronic health evaluation II.